1. Field of the Invention
The present invention relates to scroll-type compressors.
2. Description of Related Art
A known scroll-type compressor includes a fixed scroll member and an orbiting scroll member within a housing. The fixed scroll member has a first end plate and a first spiral element that extends axially from the first end plate. The orbiting scroll member has a second end plate and a second spiral element that extends axially from the second end plate. The first spiral element and the second spiral element interfit at an angular and radial offset to form a plurality of line contacts that define at least one pair of sealed-off fluid pockets. The orbiting scroll member rotates in an orbital motion with respect to the fixed scroll member. The sealed-off fluid pockets move radially inward due to the orbital motion of the orbiting scroll member. The pockets also decrease in volume, thereby compressing refrigerant gas. A plurality of bypass apertures for discharging oil included in the refrigerant gas are formed through the first end plate of the fixed scroll member. A tip seal is embedded in a front end portion of the second spiral element of the orbiting scroll member. Various measures have been undertaken to reduce interference between the tip seal and the bypass apertures. These measures include modifications to those portions of the tip seal facing the bypass apertures. Examples of such known scroll-type compressors are disclosed in Japanese Unexamined Patent Application Publication No. H11-148472 and Japanese Utility Model Application Publication Nos. S61-17490 and S61-41882.
In the scroll-type compressor disclosed in Japanese Unexamined Patent Application Publication No. H11-148472, interference between a tip seal 100 and a plurality of bypass apertures is avoided by separating tip seal 100 into a plurality of segments, as shown in FIG. 1. Moreover, in the scroll-type compressor disclosed in Japanese Utility Model Application Publication No. S61-17490, an interference between a tip seal 100xe2x80x2 and a plurality of bypass apertures is avoided by the provision of a plurality of concave portions 100xe2x80x2a formed on a front end of tip seal 100xe2x80x2, as shown in FIGS. 2a and 2b, Moreover, in the scroll-type compressor disclosed in Japanese Utility Model Application Publication No. S61-41882, interference between tip seal 100xe2x80x3 and a plurality of bypass apertures is avoided by the use of a plurality of notched portions 100xe2x80x3b formed on side walls of tip seal 100xe2x80x3, as shown in FIGS. 3a and 3b. Thus, by avoiding interference between tip seal 100 (100xe2x80x2 or 100xe2x80x3) and the bypass apertures, wear of tip seal 100 (100xe2x80x2 or 100xe2x80x3) due to contact between tip seal 100 (100xe2x80x2 or 100xe2x80x3) and the bypass apertures may be reduced or eliminated. Accordingly, tip seal 100 (100xe2x80x2 or 100xe2x80x3) may be made of a polytetrafluoroethylene (PTFE) material, for example.
Nevertheless, in the scroll-type compressor of Japanese Unexamined Patent Application Publication No. H11-148472, in which the tip seal 100 at the front end portion of the second spiral element of the orbiting scroll member is separated into a plurality of segments, the manufacturing time required to form a groove that receives the segmented tip seal may increase. Moreover, additional manufacturing time may be required to embed segmented tip seal 100 in the front end portion of the second spiral element. Moreover, additional time may be required for inventory management of segmented tip seal 100 due to an increase in the number of parts of segmented tip seal 100. Further, tip seal 100 may be attached improperly. Additionally, performance of this scroll-type compressor may decrease due to refrigerant gas leaking through defective portions of tip seal 100, which portions may be caused by errors in the manufacture of tip seal 100. Similarly, in the scroll-type compressors of Japanese Utility Model Application Publication No. S61-17490 and Japanese Utility Model Application Publication No. S61-41882, the performance of these scroll-type compressors may decrease due to refrigerant gas leaking between fluid pockets via concave portions 100xe2x80x2a of tip seal 100xe2x80x2 or notched portions 100xe2x80x3b of tip seal 100xe2x80x3.
A need has arisen to simplify the manufacture of tip seals and reduce leakage in known scroll-type compressors with an end plate of a fixed scroll member having bypass apertures and a front end portion of a spiral element of an orbiting scroll having a tip seal.
In an embodiment of this invention, a scroll-type compressor comprises a housing, a fixed scroll member, an orbiting scroll member, a drive mechanism, and a rotation prevention mechanism. The housing has an outlet port and an inlet port. The fixed scroll member comprises a first end plate and a spiral element formed thereon. The spiral element extends from a first side of the first end plate. The fixed scroll member is attached to the housing. The orbiting scroll member comprises a second end plate and a spiral element formed thereon. The spiral element extends from the first side of the second end plate. The spiral elements interfit at an angular and a radial offset to form a plurality of line contacts that define at least one pair of sealed-off fluid pockets. The drive mechanism comprises a drive shaft that is rotatably supported by the housing. Rotation of the drive shaft effects an orbital motion of the orbiting scroll member to thereby change a volume of the fluid pockets. A rotation prevention mechanism prevents the orbiting scroll member from rotating. A plurality of bypass apertures are formed through the first end plate of the fixed scroll member. A tip seal made of Polyphenylene-sulfide or Polyetheretherketone is embedded in a front end portion of the spiral element of the orbiting scroll member.
Other objects, features, and advantages of embodiments of this invention will be apparent to, and understood by, persons of ordinary skill in the art from the following description of preferred embodiments with reference to the accompanying drawings.